Irenaeus was born around 125 AD in Asia Minor, modern-day Turkey. He became a priest and was sent to the church in Lyons. He served as a missionary, peacemaker, and was the second bishop of Lyons at a difficult period of persecution and controversies. He is highly regarded by the Church for his writings, which not only laid the foundations for Church theology, but also defended and saved the Catholic faith from attacks and the danger of heresies.